Camstudio - Record screen video. Free alternative to TechSmith’s Camtasia.
Screenshot Captor - Capture, edit, and publish screenshots. Free alternative to TechSmith’s SnagIt. Very nice output.
AVG Anti-Virus - Antivirus. Effective.
CloneSpy - Duplicate file finder and remover. Saved me a bunch of time sorting through gigs of data I’ve accumulated over the last decade or so.
WinDirStat - View your directory and file size usage via treemaps. It really is quite useful.
KeePass - Password vault.
Inkscape - Vector-based drawing program.
Paint.Net - Image effects and simple editing. The “glow” effect is the best.
Notepad++ - Easy text editor with programming language syntax highlighting.
PuTTY - SSH client.
WinSCP - SFTP and FTP client.
IZArc - Archive utility, like WinZip.
Calculators (I install several)
The Entire Sysinternals Suite - Handy when you need them.
Scribus works well for deskop publishing, if you’re a WYSIWYG sort.
AM-DeadLink - Link checker for IE favorites and Firefox bookmarks.